Control valve for variable displacement compressor

Abstract

A control valve includes: a body having a control chamber communication port and a suction chamber communication port; a valve element that moves toward and away from a valve hole to close and opening a bleed valve, the ports communicating with each other through the valve hole; a solenoid to generate a drive force in an opening direction of the bleed valve; and a pressure sensing element to sense a pressure in the suction chamber or a pressure in the control chamber, and generate a counterforce against the drive force from the solenoid depending on a magnitude of the sensed pressure. An opening degree of the bleed valve is controlled so that the sensed pressure becomes a set pressure. A bleed passage for delivering the refrigerant introduced through the control chamber communication port to the suction chamber even while the bleed valve is in a closed state is formed.

What is claimed is: 
     
       1. A control valve applicable to a variable displacement compressor having a suction chamber, a discharge chamber, and a control chamber, and having a discharge capacity varied by regulating a pressure in the control chamber, the control valve comprising:
 a body having a control chamber communication port communicating with the control chamber and a suction chamber communication port communicating with the suction chamber; 
 a valve element that moves toward and away from a valve hole to close and open a bleed valve, the control chamber communication port and the suction chamber communication port communicating with each other through the valve hole; 
 a solenoid to generate a drive force in an opening direction of the bleed valve depending on an amount of supplied current; and 
 a pressure sensing element to sense a pressure in the suction chamber or a pressure in the control chamber, and to generate a counterforce against the drive force from the solenoid depending on a magnitude of the sensed pressure, 
 wherein an opening degree of the bleed valve is controlled so that the sensed pressure becomes a set pressure associated with the amount of current supplied to the solenoid, 
 wherein a bleed passage for delivering refrigerant introduced through the control chamber communication port to the suction chamber even while the bleed valve is in a closed state is formed, 
 wherein the body further has a discharge chamber communication port communicating with the discharge chamber, and 
 wherein a supply valve for delivering refrigerant introduced through the discharge chamber communication port to the control chamber even while the bleed valve is controlled is provided, 
 wherein while the bleed valve is controlled, a range in which the supply valve has a constant opening degree is present, 
 wherein a state while the bleed valve is controlled is a state in which the valve element and the pressure sensing element are connected with each other to move integrally. 
 
     
     
       2. The control valve according to  claim 1 ,
 wherein in a range in which the opening degree of the supply valve changes, a range in which the bleed valve has a constant opening degree is present. 
 
     
     
       3. The control valve according to  claim 2 ,
 wherein the constant opening degrees of the bleed valve and the supply valve are provided by clearances between valve elements and valve holes of the bleed valve and the supply valve. 
 
     
     
       4. The control valve according to  claim 1 ,
 wherein the bleed passage is an orifice formed in the body. 
 
     
     
       5. The control valve according to  claim 1 , further comprising:
 an opening/closing mechanism to open a communication passage allowing the control chamber and the suction chamber to communicate with each other depending on the amount of current supplied to the solenoid, the communication passage being formed in addition to the bleed passage. 
 
     
     
       6. The control valve according to  claim 1 ,
 wherein the valve element has a spool portion inserted into and removed from the valve hole, and 
 wherein an orifice that is the bleed passage is formed between the spool portion and the valve hole while the bleed valve is in the closed state. 
 
     
     
       7. A control valve applicable to a variable displacement compressor having a suction chamber, a discharge chamber, and a control chamber, and having a discharge capacity varied by regulating a pressure in the control chamber, the control valve comprising:
 a body having a control chamber communication port communicating with the control chamber and a suction chamber communication port communicating with the suction chamber; 
 a valve element that moves toward and away from a valve hole to close and open a bleed valve, the control chamber communication port and the suction chamber communication port communicating with each other through the valve hole; 
 a solenoid to generate a drive force in an opening direction of the bleed valve depending on an amount of supplied current; and 
 a pressure sensing element to sense a pressure in the suction chamber or a pressure in the control chamber, and to generate a counterforce against the drive force from the solenoid depending on a magnitude of the sensed pressure, 
 wherein an opening degree of the bleed valve is controlled so that the sensed pressure becomes a set pressure associated with the amount of current supplied to the solenoid, 
 wherein a bleed passage for delivering refrigerant introduced through the control chamber communication port to the suction chamber even while the bleed valve is in a closed state is formed, 
 wherein the body further has a discharge chamber communication port communicating with the discharge chamber, and 
 wherein a supply valve for delivering refrigerant introduced through the discharge chamber communication port to the control chamber even while the bleed valve is controlled is provided, 
 wherein a valve chamber is provided between the control chamber communication port and the valve hole, 
 wherein a valve element of the bleed valve includes:
 a sliding portion slidably supported in the valve hole; 
 a spool portion inserted into and removed from the valve hole; and 
 a reduced-diameter portion between the sliding portion and the spool portion, and 
 
 wherein a cut-out reaching the reduced diameter portion and the valve chamber is formed in a lateral side of the valve element, the cut-out forming the bleed passage allowing the valve hole and the valve chamber to constantly communicate with each other.